One type of field sprayer adapted for applying liquid chemical solutions (e.g., weed control chemicals or fertilizers) over fields typically comprises (1) a liquid supply assembly including a liquid supply tank and a pump, which liquid supply assembly can be mounted on the rear end of a tractor or can be in the form of a trailer adapted to be puled by a tractor, and (2) an elongate boom assembly mounted on the liquid supply assembly. The elongate boom assembly typically extends transversely across one end and for a large distance on both sides of the liquid supply assembly, and includes piping leading to a row of spaced outlet spray nozzles along its length through which liquid pumped from the liquid supply assembly is sprayed toward the ground. It is desirable to dampen or cushion the boom assembly from any shocks from or bouncing action of the liquid supply assembly, particularly because elongate end portions of the boom assembly are cantilevered and can be caused to move excessively because of such shocks or bouncing action.
One known type of support assembly for supporting a spray boom assembly from a liquid supply assembly includes first and second horizontally spaced sets of support arms with two vertically spaced support arms in each of the sets. Supported ends of the support arms are pivotably mounted on a frame of the liquid supply assembly and opposite supporting ends of the support arms are pivotably mounted on a frame of the boom assembly to afford movement of the spray boom assembly between a raised position with the support arms extending generally upwardly from the liquid supply assembly to the spray boom assembly, and lowered positions with the support arms extending generally horizontally or downwardly from the frame of the liquid supply assembly to the frame of said spray boom assembly. Hydraulic cylinder assemblies are provided for positioning the frame of the spray boom assembly at any position between its raised and lowered positions. An attempt to dampen or cushion the transfer of any bouncing action of or shocks from the liquid supply assembly to the boom assembly has been made by providing an air chamber communicating with the lines supplying hydraulic liquid to the hydraulic cylinder assemblies so that such bouncing action or shocks will cause fluid to flow out of the hydraulic cylinder assemblies and compress the air in the air chamber to provide that damping. The effectiveness of this approach is limited, however, because the passageway through which hydraulic liquid must pass into and out of the hydraulic cylinder assemblies is restricted by small orifices (e.g., 0.060 inch diameter orifices). These small orifices are provided to slow the release of liquid from the hydraulic cylinder assemblies in the event that the hydraulic lines supplying the hydraulic cylinder assemblies should break or be severed, thereby giving an operator time to stop movement of the field sprayer before the spray boom assembly strikes the ground. Those orifices, while providing that function, also limit the flow of fluid out of the hydraulic cylinder assemblies when a shock or bouncing action occurs in the liquid supply assembly, thereby limiting the amount of dampening or cushioning that can be provided by the compression of air in the air chamber.